Immunotoxicity of Disinfection Byproducts and Disinfected Water: Sensitive Assessment Using Impairment of Macrophage Anti-infection Capacity as an End Point

Drinking water disinfection, vital for public health, generates numerous disinfection byproducts (DBPs) with potential immunotoxicity, which are not well characterized. We established a novel, sensitive immunotoxicity evaluation system using impairment of macrophage anti-infection capacity as a physiologically relevant end point. A comprehensive evaluation of 29 DBPs spanning 10 structural classes revealed significant immunotoxicity differences. Critically, aliphatic DBPs exhibited substantially higher immunotoxicity than cyclic DBPs, contrasting sharply with macrophage cytotoxicity rankings, where cyclic DBPs were more potent. Quantitative structure-activity relationship (QSAR) modeling identified distinct molecular determinants: cytotoxicity depended on the lowest unoccupied molecular orbital energy (<i>E</i>_LUMO), hydrophobicity (log <i>D</i>_7.4), and total valence connection index (TVCon), while immunotoxicity correlated with the molecular zero-point energy (ZPE) and molar surface area (<i>SA</i>), suggesting divergent mechanisms. Furthermore, we developed a method combining direct (nonconcentrated) exposure with serum-free cell culture to assess the immunotoxicity of real water samples and found that water samples chlorinated for 12 h exhibited peak immunotoxicity. Notably, total organic halogen (TOX) showed a strong and significant positive correlation (<i>R</i>² = 0.9705) with immunotoxicity, and could be a potential indicator for immunotoxicity of real disinfected water.